Blended silicone lubricating fluids



2321,50"? Batented J ans 23, 1 958 United States i,.PatentfQfifice2,821,507 .:BLENDED2SILICONE LUBRIGATING- FLUIDS GordonCfGain'er and"Russell "M: Luck, Pittsburgh, Pa., assignors to Westinghouse ElectricCorporation, East Pittsburgh, Pa.,-a corporation of Pennsylvania NoDrawing. E-Appli'c'atioii August 12, 1955 .Scrial No. 528,109

Claims- ,(Cl. 252-49.6)

i The presentv invention relates to lubricants and has "particular"reference" to silicone fiuidQlubricants';having extremely lowviscosities and outstanding. lubricating jfpro'perties over "a Widerange'bfzternperatures' whereby lthey are adapted to lubricaterelatively movable metalj'to i .""metal'surfaces.

g Turbo 'jeta'nd gas turbine aircraft operate over a wide Irange'oftemperatures. 'At'high altitudes such. aircraft "frequentlyen'countertemperatures as-;l ow:as'65j"fF. Jln' addition, militaryaircraft may be subjected to ex- I trem'ely' low environmentaltemperatures in frigid or polar "climates. Suchraircr'aftiare requiredto start immediately. "jThe flatter requirementdemands "that thelubricant" be fof talowfviscositysotthat.it-isreadily pumpable attemperaturesas"l ow:as "65 "F, I I g i N V Afterthe 'plane has landedand'itheengine has been'shut "'ofi, heat from the'red-hot turbo rotorsoaks baclgalong the shaft tothe "main bearings wherein the lubricant is"subjected. to"frying temperatures of 400? Randihighcr.'rThe'lubrication of"thernovipg inetal parts in such turbo jet orrgasturbine enginesoperatipg within 'thisiwide temperature'range haspresented a problem which been difiicult to'solve. Petroleum baselubricants, evenjwhen highly refined, have not proved to be completelysatisfac- "tory. g w p x It has-been suggestedmin Ui Patent,2,4'56;49 6,"which *is assigned to the assignee of: the presentiinvent'iomf (that"organc'ssiloxane fluids comprising dimethylsilicones be used as hearinglubricants. 'Such materials have excellent heat stability and undergoaz'rema'rkably low change in viscosity 4 and a high coefiicientoffriction hasbeen found, 7 r

' The coeflicient fof-frictionfof a commercially availableidimethylsili'cone lubricating" Zfluid, representing .about'fnthe bestdimetliylsiliconei available atf the. present ..tirne,-..t isZPPLOXimHWIY 0536, steel against steel. Whensteste'dr in afFalexmachine, the dimetliylsiliconel'fltiids.give amav- "'erage wear rate,steel on steel, of "3600 wear .units per hour. f,Byicontra st',- highlyrefined petroleum tbase..lubri 'cants have coeflicients of. friction offfrom ,O .'-13,. to .020 'itinder ,the same test conditions and Falex'weartratesl'of i 0 1 2 to}: 8, .o sli b m ew lits. P h R "a a .ffparentfifrorn these datafithat in L these propertiesgattleast, the*dimethylsilicones are not. as satisfactory .Taslthe; v-petroileumlubricants. Tl Consequently, dimethylsilicones; .are suitable forlubrication use onlyjn alimited number, of ,;applications and. then,:generally, .only (under ,lightrlo'ads. Ithas beenjvdisclosedinfcopendingmpplication'Serial 1 No; 'i467g246gwhich also islassign'edto the assignee of the present inventiongthat tfluids havingtsatisfactory r nser r ss eisetei W at ha s ee aree tashsktqp smiw thsilis n atoms along the linear siloxane chain. These fluids arenous-and, in, many'bearing structures, excessive wear 50 .12 i prepared'by hydrolyzing andequilibrating selected-silicone monomerstoformfluidshaving' the formula rut-I) wherein x represents at least one:substituent selectedfrom gthqgroup consisting of chlorine;bromine,-fluorine and trilfiuoromethyl, m has an average yalue-offroml:to 4, and :nrhasanaverage value of at least 1. p

This: fluid silicone *composition has been determined to be a mixture ofsiliconeswhichdiifer from one another sronlwin rthexaluenfz n. It isrdisclosedin said application Serial lioztifigLig ldthatmefluidlsilicone fraction obtained pn frati 0iiatipn bribe. mixture of.silicones and separating f therefromthelfraetion' wherein n has a valueof 1, provides ma fluid silicone ,having excellent lubricatingproperties and goodaviscorne't-ric 'ipg erties at temperatureswithin theran e of -112,r F.-to. 400 F. "However, the mixture of silicone fluidsremaining, after the separation therefrom of the fraction. wherein W hasavalue of .1, does not have as good lviscometricnpnoperties. The mixtureof silicone fluids remaininggwhereinn hastan average value of not lessthan 2, has a freezing point of not less than 40 F. axtconsequenceythatxmixture of silicone: fluids is {not jisuitable'for use as a lubricantatextremely low environmental' ztemperatures such as 'areqoftenencountered in aircraft powered by. jet engines, since the mixture .is,a solid at 65 F.

Liquid linear organop olysiloxanes having the formula 40 where in x, mand n have the same meanings SCtiifOIth hereinabove, have beennproposedfor use as lubricants.

Such materials have excellent viscometric properties and acceptably lowviscosities at low temperatures and, as will u be seen, have goodlubrication characteristics but do not 9 =havetoptimum lubricatingproperties.

'It is known that the lubricating ability. ofvhalogensubstitutedphenylsilicone fluids is directly related-'to ,;the halogencontent of the fluid. While the introduction of the polar halogengroupvinto thesilicone'=fluid,produces a desirable enhancement of itslubricating1ability',"fit also has the adverse effect of increasing the"viscosity and via- --cosity temperature coeflicientofthefiuid,andj'alsojaising its freezing point. 7

. Thusftheincorporation of, additional halogen substituted phenyl'groupsinto siliconenfiuidsnofl the (general f *Forniula aiaboveto form a fluidhaving theformula:

whei'ein" xy m; and n have the meanings gas given herein- --above','h'as the desired resultofyincreasinglthelubricating characteristics ofthe si'licone-fluid but at the Sametime the undesired result ofincreasing its viscosity.

The resultant modified silicone fluid, therefore, still is not entirelysuitable for use as a jet aircraft engine lubricant because theadditional halogenqsubstitu't'ed phenyl groups raise the viscosity andfreezing ipoint of 3 the modified fluid to a degree such that itsolidifies at temperatures substantially above 65 F.

The object of the present invention is to provide silicone fluidlubricants having outstanding lubricating properties and low viscositiesat temperatures within the range of from about -65 F. up to about 400 F.by blending a silicone fluid having a relatively low viscosity at 65 F.and a relatively low halogen content with a selected proportion of atleast one silicone fluid having a relatively high viscosity at -65 F.and a relatively high halogen content.

Another object of this invention is to provide an efficacious method oflubricating metal-to-metal surfaces by applying thereto a fluid siliconelubricant capable of fluid flow at temperatures within the range of fromabout 65 F. up to about 400 F., the lubricant comprising a blend of asilicone fluid having a relatively low viscosity at 65 F. and arelatively low halogen content with a predetermined proportion of atleast one silicone fluid having a relatively high viscosity at 65 F. anda relatively high halogen content.

Other and further objects of the invention will, in part, be obvious andwill, in part, appear hereinafter.

In the attainment of the foregoing objects and in accordance with thepresent invention, there is provided a fluid silicone lubricantcomprising a mixture of (A) from one to twenty-five parts by weight of aliquid linear organopolysiloxane having the formula:

(3H5 CH: (3H5 I @rt a In G H: C H3 0 CE:

for (B) each one part by weight of at least one liquid linearorganopolysiloxane selected from the group consisting oforganopolysiloxanes having the formulae:

wherein x represents at least one substituent selected from the groupconsisting of chlorine, fluorine, bromine, and trifiuoromethyl, m has anaverage value of from one to to five inclusive, and n has an averagevalue of not less than two.

The mixture of liquid linear organopolysiloxanes thus described has alow viscosity at temperatures down to -65 F. and excellent lubricatingproperties at any temperature throughout the entire range of -65 F. to400 F. This result was not to be expected because the linearorganopolysiloxanes individually have widely diflering properties. Thus,the organopolysiloxanes (a) and (b) have excellent lubricatingproperties but are extremely viscous at temperatures above 65 F. whereassiloxane (A) has poorer lubricating properties, but still has a lowviscosity at temperatures as low as 65 F.

The liquid linear organopolysiloxane identified as (A) above comprisesessentially a linear or unbranched siloxane having repeating groups andterminal groups (311: Sl0-- 1 Q In CH3 2 wherein x and m have themeanings set forth hereinabove.

The liquid linear organopolysiloxane (A) may be obtained by hydrolyzingand equilibrating a mixture of silane monomers, one of which has theformula (H) CH1 and the other of which has the formula wherein x and mhave the meanings given hereinabove and Y is a hydrolyzable group.

The hydrolyzable groups, represented by Y in the above formulae, may beeither alkoxy, aryloxy, halogen, acyl 01 amino groups. When thehydrolyzable group is an alkoxy material, the alkyl portion thereof maybe either primary, secondary or tertiary, for example, methyl, ethyl,propyl, butyl, isopropyl, isobutyl, secondary butyl, tertiary butyl,hexyl and the like. When the hydrolyzable group is an aryloxy group, thearyl radical may be a phenyl radical or a substituted phenyl radical. Inplace of the alkoxy and aryloxy groups just described, any of thehalogens or an amino or acyl group may be used as the hydrolyzable groupin accordance with this invention. It is preferred to use those silanemonomers having hydrolyzable radicals which are halogen groups sincesuch monomers are more readily available commercially.

Examples of preferred silaue monomers having the structure set forth inFormula II hereinabove include x,xdichlorophenyldirnethylchlorosilane,3,4-dichlorophenyldimethylchlorosilane, x,x,xtrichlorophenyldimethylchlorosilane, and3-trifluoromethyl-4-chlorophenyldimethylchlorosilane.

The following example illustrates one method for preparing a liquidlinear organopolysiloxane having the structure indicated in Formula Aabove. The parts indicated throughout the specification and in theappended claims are by weight unless otherwise noted.

EXAMPLE I A mixture of 774 parts (6 mols) of dimethyldichlorosilane and479 parts (2 mols) of x,x-dichlorophenyldimethylchlorosilane was stirredin a suitable vessel.

The mixture then was hydrolyzed by admixing with a large excess ofcrushed ice, the temperature of the materials being maintained withinthe range of 0 C. to 15 C. The mixture was stirred rapidly and a stickysilicone mass formed and deposited on the stirrer and sides of the flaskas hydrolysis proceeded. The aqueous hydrochloric acid which formedduring hydrolysis was decanted from time to time and fresh ice and waterwere added to minimize the formation of a strong hydrochloric acidsolution. After the hydrolysis had proceeded substantially tocompletion, the mixture was allowed to warm up to room temperature andwas vigorously stirred for about 18 hours. At the end of this time themixture was permitted to stand and separate into a fluid silicone layerand an aqueous acidic layer. The silicone layer was withdrawn, washedwith water and then dried over anhydrous sodium sulphate to yield 2635parts of an anhydrous silicone oil. The latter was chilled to atemperature of from 10 C. to 20 C. and was equilibrated by the dropwiseaddition of l3l.75 parts (5% by volume) of concentrated sulfuric acid.The acidified mixture was stirred for 60 hours at 20 C. to 25 C. Theequilibrated silicone emulsion P i was poured into a large excess ofcrushed ice. After a e-ares wherein n a ea r nq f a T i i i n a or fi1=w 1m= ha a: bw iri cosity, 6500 cen'tistokes, at -65 F. and lubricatingproperties' as determined'by the Shell Foiir Ball E'. P: Tsta's follow:

Applie'cl' load on Average-sear diameterham; i .0 .37

so 7.47 .58 5'0 .61 .93 1'0 so 1:05 1,93 Weld This-silicone fluid'hadan'i'mrnediate seizure value'of 90 kg; anda Weld of lOO kg.

The liquid linear organopolysiloxane (a) used informing the'blendedfluid silicone lubricant of this invention may be obtained byhydrolyzing and equilibrating a selected group of silicone monomers toform a fluid silicone composition as described in application Serial No.467,246. The silicone composition comprises a group ofliquidsilic'oneswhich differ from one" another only in the-value of n, as set forthinFormula-labove. The-mixture is-fractionated and separated into twoportions One portion, wherein n has a value of 1, maybe used directlyjet engine lubricant in accordance with the teachings of applicationSerial No; 467246; The" other portion,

wherein n'has an average valueo f'n'ot' less than Z Corn prises theliquidlinear organo blysiloxane (a) or thisinvention.

The liquid linear organopolysiloxane (a) comprises ess'e'ht ially linearor unbranched siloxans having repeating ligfoups' and terminaltrime'thylsilheinioxa'ne grou 's GHa-Si-0- 1 {3H3 H one convenient"method of prepann the liquid linear organopolysiloxane" (:1) compriseshydroly'zin'g and equilibratin'g a mixture of silanemonorners',oneofw'hich has the formula and the other of whic li'has'theformula V- YCHI wherein 'x andn'r' have the meanings given hereinahov'e and-Yrepresents*hydrolyzable groups. The fluidthusoiitained is a mixture ofsilicones which difler from unearother only in the value of n asindicated in Formula I above or more particularly in the number ofsubstituted phenyl groups in siloxy groups present in the molecule. Thefluid is fractionated torecover only those silicones wherein n intheFormula I has anaveragevalue of not less than 2;

7 Examples of preferred silane monomers having the structure set forthin Formula'IV hereinabove include x,xdichlorophenylmethyldichlorosilane, 3,4 dichlorophenylmethyldichlorosilane, x,x,x,-trichloropheuylmethyldichloro'silane, and- 3 trifluoromethyl 4 chlorophenylmethylflichlhrosilane. v

The next two examples illustrate the preparation of liquid linearorganopolysiloxanes having the structure illustrated in Formula a above.

EXAMPLE H A mixture of monomers-Was prepared by stirring 2232 parts (8mols) of 3;4-dichlorophenylmethyldichlorosilane and 1736 parts l6'rnols) of trimethylchlorosilane in a suitable vessel. The-mixture thenwas hydrolyzedand equilibrated in accordance with the proceduredescribed in'EXarIipI' Ii The'dried siliconeo'il mixture then'was placedin a Claisen distillation apparatus, heat and vacuum were applied andthe fractions listed in Table I were obtained.

Table I Boiling Pressure Viscosity (cs.) v Fraction Point, (mm.)Freezing F. 'Hg- I Point, F.

65 F. 100 F. 210 F. 7

It; 200-220 1 400 2. 7 I r4 Below -04 II 220 290 1 I750" 3.9 1.9 Below94 III- a- 1 280-365 0.85 Solid 10.2 4.-0 60 IV Pot Solid 66. 1 12. 0 13Residue A composite silicone fluid comprising fraction'III was found tohave the following formula:

1 CH0 CHs-Sb-O- 811-0 SiCHs 0 HI .5 CH3 n C H:

wherein n has an average value of 2.75. The lubricating properties ofthis mixture of fractions were determined by the Shell Four Ball E. P.Test for steel against steel with the following data bein'gobtained:

Applied load (kg.): Average scar diameter (mm.)

aaamo'z 7 EXAMPLE III A monomer mixture comprising 2232 parts (8 mols)of x,x-dichlorophenylmethyldichlorosilane and 1736 parts (16 mols) oftrimethylchlorosilane was hydrolyzed, equilibrated and vacuum distilledin a Claisen distillation apparatus in accordance with the methoddescribed in Example I. The properties of the fractions obtained arelisted in Table II.

Table II Boiling Pressure Viscosity (cs.) Fraction Point, (mm) FreezingF. Hg Point, F.

65 F. 100 F. 210 F.

I 210-290 1 3, 270 5. 5 1. 99 Below 94 II 290-380 1 Solid 38.90 6.15 17III Pot Solid 815. 6 21. 41

Residue The silicone fluid comprising fraction II was found to have thefollowing formula:

wherein n has an average value of 2.75.

The lubricating properties of this mixture of fractions, as determinedaccording to the Shell Four Ball E. P. Test for steel against steel,were as follows:

Average scar diameter (mm.)

The liquid linear organopolysiloxane identified as (b) above comprisesessentially a linear or unbranched siloxane having the followingrepeating groups:

CH: Si-O- and Si0 (IE3 and terminal groups:

z". CH3

where x and m have the meanings set forth hereinabove.

The liquid linear organepolysiloxane (b) may be prepared by hydrolyzingand equilibrating a mixture of silane .monomers in much the same way asdescribed hereinlabove with respect to the preparation of theorganopoly- 8 siloxanes identified as (A) and (a). Similar silanemonomers and similar hydrolyzing and equilibrating agents may be used asin previous examples.

The following example illustrates one method for preparing a liquidlinearorganopolysiloxane having the structure indicated in Formula babove.

EXAMPLE IV A mixture of 497 parts (2 mols) ofx,xdichlorophenyldimethylchlorosilane, 1548 parts (12 mols) ofdimethyldichlorosilane, and 780 parts (3 mols) ofx,X-dichlorophenylmethyldichlorosilane was hydrolyzed by adding the samedropwise, to a large excess of crushed ice, the temperature beingmaintained at 5 C. to 15 C. The aqueous hydrochloric acid solution whichformed was decanted several times from the cloudy oil formed during thehydrolysis. More ice was added from time to time to reduce the acidconcentration. After completion of the silane addition, the mixture wasallowed to warm to room temperature and was stirred over night. The oilwas then separated from the aqueous hydrochloric acid, washed two timeswith water, and dried over anhydrous sodium sulfate. The dried siliconefluid was cooled to 10 C. to 20 C. and was equilibrated by the dropwiseaddition of 70 parts (5% by volume) of concentrated sulfuric acid. Afterbeing stirred for hours at 20 C. to 25 C., the silicone oil-acid mixturewas poured onto a large excess of crushed ice. The oil was separatedfrom the acid, neutralized by the addition of an aqueous sodiumbicarbonate solution, and was finally dried over anhydrous sodiumsulfate. The oil thereby obtained then was stripped for two hours at 275C. under a vacuum of 6 to 7 millimeters of mercury in a Claisendistillation apparatus'.

This silicone oil was found to have the formula Ch CH3 CH3 CH3 Cl: t. o[t. o] SH, mg

(3113 (1113 n CH; 11' (3H3 wherein n has an avearge value of 12 and nhas an average value of 3. This liquid linear organopolysoloxane freezesto a solid at temperatures below 45 C. Its lubricating properties asdetermined by the Shell Four Ball E. P. Test are as follows:

Average scar Applied load (kg): diameter (mm.)

The following examples are illustrative of fluid silicone lubricantsobtained by blending the several liquid linear organopolysiloxanes inthe proportions herein described.

EXAMPLE V Four parts by weight of the liquid silicone fluid prepared asdescribed in Example I were thoroughly stirred and admixed together withone part of the liquid silicone fluid prepared as described in ExampleII. The stirring was continued until a clear homogeneous solution wasobtained. The fluid silicone lubricant thus obtained has a viswlty at 65F; of: 12,590: ce'ntistok'es and: a freezing pbint-of He1nw 9 t" Thelubricatingfp'ropertie's' of this material as uetermined by the ShellFour'Ball E. P. Tese fife 'as rouows:

Average scar Applied load (kg.) diameter (mm) 9 1. 1..-. .1. n .mo 7 1102.70 120 Weld This blendedoilis suitable for use as a luliricant in jetaircraft engines.

parts of tile organopolys'iloxane of Example I were admixed with onepart of the organopolysiloxane of Example III. This material had aviscosity at -65 F. of 26,600 and a freezing? point of 72 F. Thelubricating propertie's 'of this material as determined in the ShellFour Ball E; P. Test-are as follows-:

Average scar Applied load (kg): diameter (mm.) .29

a weld r 100 kg; It isa'n ex'cellent lubrican't'fo'rsuch applications assteam tii'r' b'ifie's and electr-ic motors:

EXAMPLE VII= A flilid siiieene'liieribant we repared by admix'iiig threeparts of the organopolysiloxane of ExampleI with one part 'of theof'g'ano'polysildxan'e of Example II. This fluid lubricant hadaviscosity at -65 F. of 14,000 and a freezing-point of below "94' F. Thelubricating characteristics of thissiliconelubricant as determined inthe Shell Four Ball E. P. Test aie'a's' fdllowsz 7 Average scarwppiiedqbaaukgue diameterIm'm.) 20 .34 30 .34 40 .50 .62 M .73 70 1.0180 1.07 90 1.03 100 2.21

.140: Weld izmsz iitiia naa se m1 "edia'te seizure valiie of 90'" kg.and

a weld of 110 kg.

This silicone fluid is"'a r1- excellent lubricant for use in jetaircraft engines.

EXAMPLE VIII A fluid silicone lubricantwa s prepared by mixing threeparts of organopolysiloxa'ne of Example I with one part of theorganopolysiloxane of Example III. This silicone lubricant had aviscosity at of 42.200 anda 10 tics of this lubricant-as determihe'd inthe Shell Four Ball E. P. Test areas follows:

Applied load Average scar diameter M M... 1.. 1. 09 1.11 1.56 1.86 WeldThis fluid had an immediate seizure value of 90kg. and w d U19 k Thisfluid is suitable for suchapplications as steam turbine lubricationsystems. It also may be used as an electric motor lubricant.

A fluid silicone lubricant was prepared by admixing two parts of theorgaridpolysildxaneof Example I with one part of theorgafiopo'lysiloxane of Example II. This material had a viscosity of16,400 centist'okes a't' -65' F. and a freezing cinfdf -*80 F. It'slubricatingTchara'cteri'stics asdete'r'mined in" the Shell Four Ball E.P. Te'st are as follows:

Applied load Average scar diameter (kg.):- (mm) '20 M .39 '3 0 2 .4 540-; 50 Y A 60 a .77 70 .97 80 .97 90 1'l0;- Weld This material had animmediate seizure value ofi 90 kg. and a weld of 110 kg.

This fluid is an excellent lubricant for use in jet aircraft engines.

EXAMPLE X' A fluid silicone lubricant Was prepared by mixing two partsof the organopolysiloxane of Example I withone part ofthe'organopolysiloxarieofExample III; The resuiting fluidsiliconeluhiicant h'a'd'a' viscosity at"-6 5': or 70,800 centi'stokes"and a' freezing p'oint' of -'73"F. The lubricatingcharacteristic'sjoftl'iisu'iiatfial sedate?- "fwfizingipoiimer "er- 74The lubricating cha'ract'eris-"76 tutbinEdutitiCMibn- System53 itablefor ma: appfieatiefisas- -steam.

1 1 EXAMPLE XI A fluid silicone lubricant was prepared by admixing 8parts of the organopolysiloxane of Example I with one part of theorganopolysiloxane of Example II and one part of the organopolysiloxaneof Example IV. This material had a viscosity of 37,000 centistokes at 65C. and a freezing point of 85 C. to 90 C. Its lubricatingcharacteristics as determined in the Shell Four Ball E. P. Test are asfollows:

The low viscosity and freezing point of this blend of silicone oils andits excellent lubricating properties in combination with its highthermal stability when admixed with conventional refrigerants such asdichlorodifluoromethane makes it particularly suitable for use as alubricant in refrigerator compressors.

EXAMPLE XII A fluid silicone lubricant was prepared by admixing 15 partsof the organopolysiloxane of Example I with 8 parts by weight of theorganopolysiloxane of Example IV. This material freezes at a temperaturebelow 60 C. and has the following lubricating properties as determinedby the Shell Four Ball E. P. Test.

Applied load Average scar diameter (kg.) (mm.)

100 2.11 110 2.40 120 Weld When jet engines have the fluid siliconelubricants of Examples V, VII, and IX applied to the ball and rollerbearings, accessory transmissions, gears, hydraulic pumps, and the like,such component parts are lubricated satisfactorily at all operatingtemperatures down to as low as -65 F. The fluids do not freeze attemperatures as low as 65 F. nor do they decompose or pyrolyze attemperatures as high as 400 F.

The fluid silicone lubricant blends prepared in Examples VI, VIII, and Xare excellent for application 'in steam turbine lubrication systems andare excellent lubricants for electric motors and in gear boxes and otherapplications. Such lubricants do not have the low viscosity at thelowest temperatures of the lubricant blends of Examples V, VII, and IX,however, electric motors, gear boxes and steam turbine lubricationsystems ordinarily are not subjected to such low operating temperatures.

The fluid silicon lubricant blends of Examples XI and XII are excellentfor use in refrigerator compressors since they have low viscosities andfreezing points, excellent lubricating ability, and are thermally stablein the presence of the halogenated aliphatic refrigerants such .asdichlorodifluoromethane conventionally used.

Suitable halogenated aliphatic refrigerants comprise derivatives ofmethane and ethane wherein hydrogen is completely replaced by chlorineand fluorine, and not over a single hydrogen atom remains, there beingat least one chlorine and one fluorine atom in each molecule. Examplesare dichlorodifluoromethane, trifluorotrichloroethane anddifiuorochloromethane.

While the present invention has been described with particular referenceto certain specific embodiments thereof, it will be understood, ofcourse, that certain changes, substitutions and modifications may bemade therein without departing from its true scope.

We claim as our invention:

1. A fluid silicone lubricant consisting essentially of a mixture of (A)from one to twenty-five parts by weight of a liquid linearorganopolysiloxane having the formula:

(IE3 (IE3 (IE3 Zn CH3 CH3 n CH3 In for (B) each one part by weight of atleast one liquid linear organopolysiloxane selected from the groupconsisting of organopolysiloxanes having the formulae:

(1H3 CH3 CHs-Sl-O -S|l0 Sl-CH CH: (Hit 11 CH:

and

In $11.1 (3H3 (3H3 I. @r- .0

CH: CH: n CH: 7| C 3 wherein x represents at least one substituentselected from the group consisting of chlorine, fluorine, bromine, andtrifluormethyl, in has an average value of from one to five inclusiveand n has an average value of not less than two.

2. A fluid silicone lubricant as set forth in claim 1 wherein the liquidlinear organopolysiloxane (A) has the formula:

(I311: (I113 (EH3 C12 23 0- v C 2 CH1 CH3 n CH3 wherein n has an averagevalue of 6.

3. A fluid silicone lubricant as set forth in claim 1 wherein the liquidlinear organopolysiloxane (a) has the formula:

wherein n has an average value of 2.75.

4. A fluid silicone lubricant as set forth in claim 1 wherein the liquidlinear organopolysiloxane (a) has the formula:

wherein n has an average value of 2.75.

5. A fluid silicone lubricant as set forth inclaim 1 wherein the liquidlinear organopolysiloxane (b) has the formula:

012 (3H6 CH3 IJ a C12 2,662,055

wherein n has an average value of 12 and n has an 10 average value of 3.

References Cited in the file of this patent UNITED STATES PATENTS CookSept. 26, 1950 Wilcock Apr. 3, 1951 Kohl May 26, 1953 Towne Dec. 8, 1953Burkhard Sept. 21, 1954 Linville Mar. 27, 1956

1. A FLUID SILICONE LUBRICANT CONSISTING ESSENTIALLY OF A MIXTURE OF (A)FROM ONE TO TWENTY-FIVE PARTS BY WEIGHT OF A LIQUID LINEARORGANOPOLYSILOXANE HAVING THE FORMULA: